T-2 toxin (T-2), a sesquiterpene compound, is one of the most toxic in trichothecene mycotoxins. It produced by various species of Fusarium, mainly from F. acuinatum, F. poae, F. langsethiae, and F. sporotrichioide with an extensive distribution and be seriously harmful to the health of human and livestock. Toxic effects of T-2 include acute toxicity, subacute toxicity, chronic toxicity, three induced effects, immune toxicity and damage to blood system and soft tissue. The toxicity of T-2 toxin is quite stable. Its toxicity is still not reduced when it is placed for 6 to 7 years under room temperature or heated for 1 hour by 100-120° C. Due to its severe toxicity, international attaches great importance to the harm of T-2 toxin to human and livestock. Early in 1973, T-2 toxin was ranked as one of the most dangerous source of food pollution in nature by FAO/WHO. More extensive and in-depth researches on T-2 toxin have been carried out after the “Yellow rain poisoning” incident.
Recently, measurement methods available for T-2 toxin mainly include thin layer chromatography (TLC), gas chromatography (GC), liquid chromatography (LC), liquid chromatography/mass spectrometry (LC-MS), enzyme linked immunosorbent assay (ELISA) and so on. TLC is cheap in analytical cost, but suffer the problems of tedious operations and weak reducibility. GC and LC methods cannot directly determine T-2 toxin in samples and need a derivatization process. The derivatization of T-2 toxin for GC method mainly based on trimethyl silylation and fluorine acetoxylation. The derivatization reagent for LC method is Isocyanate. And the toxic chemical reagent was used in the process of measurement. LC-MS method offers the merits of sensitivity, simplicity in sample preparation, and no need for derivatization processing, but is expensive in cost. Antibody-based immunoassay often possesses the advantages of simple operation, high sensitivity, availability for a large number of samples, and no need for large and expensive equipment. However, it also suffer from the problems including the false positive rate is relatively high, and the quantity is not accurate enough. Moreover, as a small molecule semi antigen with a molecular weight of 466 g/mol, T-2 toxin does not have immunogenicity so that it is necessary to combine with the large molecule carrier protein to prepare the complete antigen to stimulate the secretion of antibodies. The process is not only cumbersome, time-consuming and costly, but the stability of the antibody batches produced is not as high as the oligonucleotide. And the antibody storage conditions are also more stringent than the oligonucleotide.
Recent years, as a potential substitute for antibody, the study on oligonucleotides aptamer is more eye-catching. Aptamers are a cluster of small molecules DNA or RNA fragments generated by systemic evolution of ligands by exponential enrichment (SELEX) technology and can selectively bind to their target molecules. SELEX technology is a new combined chemical technology developed in 1990s, which has the characteristics of economy, simple, rapid, wide application range and so on. SELEX technology using molecular biological technology to construct the synthetic random oligonucleotide library in which the middle random sequence length generally is about 20-40 nt and the primer sequences at both ends generally is about 20 nt. The library capacity is about 1013-1015 range. Because the single stranded oligonucleotide random sequence is easy to form convex ring, hair clips, holidays, G tetramer as secondary structure, it can combine with protein, peptides, drugs, amino acids, organic compounds, and even metal ions to form the complex with a very strong bonding force.